The present invention relates to a control apparatus of an automated transmission mounted on a motor vehicle, and more particularly to a technique applied to the automated transmission having a plurality of transmission gear trains.
A manual type transmission (MT) executing a gear change operation by a manual operation of a driver includes an input shaft connected to an engine and to which a plurality of drive gears are attached, and an output shaft connected to a drive wheel and to which a plurality of driven gears forming pairs together with the drive gears are attached, in which a plurality of transmission gear trains are provided between the input and output shafts. In the MT, a gear change operation, i.e., a shift change is performed by manually switching a switching mechanism such as a synchromeshed mechanism for switching a gear train, that is, a gear pair among a plurality of transmission gear trains after disengaging a clutch at a time of changing gear, thereafter connecting the clutch.
When automatically executing the shift change and the clutch operation by a hydraulic actuator, it is possible to obtain an automated manual transmission based on a structure of a manual type transmission. This type of automated manual transmission has an advantage that a number of the parts can be reduced in comparison with a normal torque converter type automatic transmission (AT) having a planetary gear in an automatic gear change mechanism so as to make it easy to lighten, and an advantages that a power transmitting efficiency of a drive system is higher than that of the automatic transmission of the normal torque converter type.
As this type of automated manual transmission (hereinafter, simply referred to as AMT) having a plurality of transmission gear trains, there is a structure having a main clutch provided between a crankshaft and an input shaft and switching thereof from a engaged condition to a disengaged condition, and vice versa, a hydraulic bypass clutch of a multi-disc type for preventing a torque disconnection from the input shaft to the output shaft at a time of the gear change operation. For example, such an AMT is disclosed in Japanese Patent No.2703169, and an operation of the clutch in the manual type transmission is automated by a hydraulically driven actuator.
In the AMT, the structure is made such that one gear pair executing a power transmission is suitably switched by the synchromesh mechanism, and the engaged gear pair are switched while transmitting the torque from the input shaft to the output shaft by switching the bypass clutch to connection state at the time of changing gear, thereby intending to prevent the torque disconnection at the time of the gear change operation.
On the other hand, the gear pair is also switched in the case of backward moving of the vehicle. When the driver operates a select lever to select a backward moving stage (a reverse range: R), the gears at the input shaft and the output shaft are engaged with each other via a reverse idler gear, so that the output shaft is rotated in a reverse direction at the time of the normal traveling. A method of connecting the reverse idler gear includes a method of connecting the gears by the synchromesh mechanism provided at the input shaft or the output shaft in the same manner as that of the forward moving stage and a selectively sliding method of moving the reverse idler gear in an axial direction so as to engage with both of the gears. Further, in Japanese Patent No. 2703169 mentioned above, there are shown a structure in which the reverse idler gear is initially engaged with the gears for reverse rotation in the input and output shafts so as to connect the gear for reverse rotation in the output shaft to the output shaft by using the synchromesh mechanism, and a structure in which both of the synchromesh mechanism and the selectively sliding type are used.
In this case, in the AMT mentioned above, when using a wet type clutch for the main clutch, the input shaft rotates in a forward moving direction due to a drag torque of the wet type clutch even when making the clutch in a disconnection state. Accordingly, in the case that the selectively sliding type mentioned above is employed for the reverse gear train, and a reverse gear is selected from a neutral gear or a forward moving stage, there are problems that the gear for a reverse rotation does not well engage with the gear of the input shaft, and gear noises may occur.
In this respect, Japanese Patent No. 2873690, discloses a structure in which means for quickly discharging a lubricating oil is provided in the wet type clutch, thereby reducing the drag torque left at the time of disengaging the clutch and an inertia of the input shaft. Accordingly, the drag torque at the time of changing the gear is securely reduced, and an engagement of the gears for reverse rotation can be improved. However, in accordance with the structure mentioned above, there is a problem that a complex lubricating circuit for discharging the lubricating oil is required, whereby the structure of the apparatus becomes complex and large-sized. Further, it is impossible to make the drag torque zero even by the structure mentioned above, and so that is not a way to basically solve the problem.
An object of the present invention is to make it possible to securely and smoothly execute a shift operation to a reverse gear for a short time in spite of using a clutch having a drag torque.
In accordance with the present invention, there is provided a control apparatus of an automated manual transmission comprising an input shaft provided with a plurality of drive gears, an output shaft provided with a plurality of driven gears engaged with the drive gears, a reverse idler gear arranged between the input shaft and the output shaft and engaging with gears for backward movement respectively provided at the input shaft and the output shaft when a backward moving stage is selected as a drive mode of the vehicle, and a bypass clutch capable of selectively transmitting or shutting a power of the input shaft to the output shaft, wherein the bypass clutch is temporarily engaged before the reverse idler gear and the backward moving gears are engaged with each other when the backward moving stage is selected.
According to the present invention, when the backward moving stage is selected, the bypass clutch is engaged so as to restrict the rotation of the input shaft before the reverse idler gear and the backward moving gears at the input and output sides are engaged with each other, so that it is possible to restrict the rotation of the drive gear so as to smoothly engage the reverse idler gear with the backward moving gears. Accordingly, the control apparatus of the present invention can prevent the gear from failing to be properly connected and prevent the gear noise from occurring when shifting to the backward moving stage.
Further, in accordance with the present invention, there is provided a control apparatus of the automated manual transmission comprising the input shaft provided with a plurality of drive gears, the output shaft provided with the plurality of driven gears engaged with the drive gears, the reverse idler gear arranged between the input shaft and the output shaft and engaging with the gears for the backward movement respectively provided at the input shaft and the output shaft when the backward moving stage is selected as a drive mode of the vehicle, and a bypass clutch capable of selectively transmitting or shutting the power of the input shaft to the output shaft, wherein the reverse idler gear and the backward moving gears are engaged with each other after the bypass clutch is engaged to stop the rotation of the input shaft when the backward moving stage is selected.
According to the present invention, when the backward moving stage is selected, the reverse idler gear and the backward moving gears at the input and output sides are engaged with each other after the bypass clutch is engaged so as to stop the rotation of the input shaft, so that the reverse idler gear can be engaged in a state of stopping the rotation of the drive gear. Accordingly, it is possible to smoothly engage the reverse idler gear with the backward moving gears so as to prevent the gear from failing to be connected and prevent the gear noise from occurring.
Further, in accordance with the present invention, the control apparatus of the automated manual transmission allows the drive mode to change to the backward moving stage only when operating a foot brake. Accordingly, it is possible to execute a shift operation to the backward moving stage just in a state of stopping the vehicle, whereby it is possible to prevent the vehicle from forward moving due to an inertia torque of the input shaft and a drag torque of the main clutch when engaging the bypass clutch.